1. Field of the Invention
This invention relates to a method of preparing a resin and a coating composition containing the resin, and more particularly to a method of preparing a water and/or alcohol soulble resin and a coating composition containing such resin.
2. Prior Art
Efforts have been made to develop water and/or alcohol soluble resins, since they may be used for preparing printing inks such as water soluble gravure inks or flexo inks or coating compositions such as water or alcohol soluble paints, which are advantageous in preventing pollution problems for the reason that they cause lesser air pollution as compared to the inks and paints containing hydrocarbon solvents such as toluene. The conventionally known water soluble resins include, for example, maleic acid resins modified with rosin having high acid values and shellac, the water-proof and antifriction properties of which are, however, not satisfactory. Besides they are disadvantageous in that the costs and supply thereof are unstable since they are made from natural resources. Synthetic resins such as copolymers of styrene and acrylic acid have been developed. However, they have disadvantages in that the stability, antifriction property and water-proof property thereof are unsatisfactory when used for inks because of their high acid values. While maleic acid resins having high acid values, nitrocellulose and polyamide resins have been know as the conventional alcohol soluble resins, they are not sufficiently satisfactory because of the disadvantages in that their pigment dispersion properties are poor so that they are not conveniently used for high speed printing.